1. Field of the Invention
The present invention relates to surgical orthopedic instrumentation and more particularly relates to an improved method and apparatus for milling a patient's bone tissue with instrumentation that can ream a patient's intramedullary canal in-situ during orthopedic surgery. A pattern constrains movement of a cutting tool, or a tracing stylus rigidly affixed to the cutting tool. Inadvertent travel of the cutting tool beyond the cutting field is prevented by the pattern.
2. General Background
There are existing milling devices used to prepare the femur prior to surgical implantation of a hip prosthesis. Attempts have been made in the past to automate the milling process. One such robotic product from Integrated Surgical Systems, Inc. is a product known by the trademark as "Robodoc".
Some patents have been issued which relate generally to milling instrumentation that includes a guiding system.
The Sulzer U.S. Pat. No. 4,777,942 discloses a surgical instrument for inner femur cutting. The '942 patent discloses a milling cutter on a spindle, joined to a gauge, with the spindle ending in a shoe. The apparatus of the '942 patent provides a curved instrument for cutting a curved contour inside the cavity of the femur.
U.S. Pat. No. 4,284,080 discloses a ball and socket insertion for hip joint prosthesis using curved cutters of a milling tool to shape the convex surface of the femur.
U.S. Pat. Nos. 4,197,645 and 4,279,598 issued to H. Scheicher each disclose a bone cavity milling head which has two cutters on offset axes driven at the same time.
U.S. Pat. No. 4,466,429 discloses a bone recess forming instrument which incorporates a machine driven tool having two rasp halves shaped to suit the recess.
French patent 223972 issued to Ceraver discloses an artificial hip joint fitting apparatus that includes a drilling jig in a round cutter head for a retaining boss socket.
The Kuhlmann British patent GB1394799 discloses a milling machine controlled by a pantograph. Kuhlmann also received a patent for a pattern controlled milling machine with a pantograph and line scanner, U.S. Pat. No. 3,581,622.
British patent GB1482848 discloses a templet control mechanism for a shoe upper milling machine. The mechanism is constructed to simplify set-up and operation. A vertical stack of different templates is provided to be contacted by one or more moving styli. The tool involved traces the templet outline on a shoe upper.
French patent 7533306 has been assigned to A. Lora that allows accurate and rapid tracing of ellipses of all sizes. It has slides in guides at right angles to each other.
R. Lopez was assigned patent FR2255996 on a machine for reproducing models through the use of a motor driven slide system for tracing a finger-controlling tool.
A German patent, DE2,848,602 was issued to Karl Harlan for a copying pantograph for milling small work pieces. It can be operated with a hand held power drill mounted in a U-shaped bracket.
U.S. Pat. No. 4,176,585 discloses a universal pantograph pattern with a number of interconnected arms, and a cutting tool for milling circular and eccentric shapes, angles, and lines.
U.S. Pat. No. 3,919,919 discloses a three dimensional cutting machine with pantograph control.
U.S. Pat. No. 3,863,543 discloses a pattern transmitting device for three dimensional working. The apparatus includes a drawing reader which follows the outline of a drawing controlling the pantograph and tracer.
U.S. Pat. No. 4,461,082 discloses a pantograph mechanism for an engraving machine. The machine is pivoted to slide about a vertical axis, with the tool holder prevented from pivoting.
U.S. Pat. No. 4,790,852 includes a description of canal preparation which are essentially a match to the shape of a modular sleeve.
Two recently issued patents that relate to bone milling include U.S. Pat. No. 5,047,033 issued to Fallin and assigned to the assignee of this application. The other recently issued patent relating to milling is U.S. Pat. No. 5,190,547 issued to Barber, Jr. et al. entitled "Replicator For Resecting Bone to Match a Pattern". The '547 patent relates to a device for resecting a bone utilizing a pattern to control the cutting tip for the resection. The device has a frame with a pattern holder and a bone holder. A tool holder mounts to the frame by means of a four bar linkage assembly. The tool holder has a cutting tool and a probe mounted to it. The four bar linkage allows two dimensional movement of the tool holder, but constrains the tool holder to always be in parallel with a line extending through the pattern holder and bone holder.